<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>任意位置的内外JS</title>

    <!--内部直接结合-->
    <script>
        alert("Hello World!");
    </script>

    <!--外部结合-->
    <script src="js/a.js"></script>
</head>
<body>
    注意加载顺序!
</body>
</html>